Water walking allows neighboring rat walk on the water too, in a sense
While I used water walking, a rat noticed me and walked a bit lower than water level, but still like on solid ground (that is, without touching the bottom) straight to me and attacked. It would not be able to attack me if it drowned properly, as it should. In vanilla it wouldn't probably get into the water in the first place, although I haven't tested this (no Windows machine right now).
(RM-3657 from redmine: created on 2016-12-13 by Mark Karpov, )